Sanding machine for bowling alleys

ABSTRACT

A sanding machine for bowling alleys including a sanding drum mounted for rotation about an axis approximately normal to the length of the alley. The drum is journalled rigidly at the front of a unitary frame which rides on a bogie on the alley and is balanced toward the rear of the bogie. The angular orientation of the frame is adjustable relative to the bogie, laterally to ensure level sanding, and also longitudinally to control the weight placed on the drum. The speed of advance of the machine along the alley is controlled responsively to variations in the load encountered by the motor that drives the drum so that the advance is slowed whenever the drum encounters a high area that requires more sanding than an area just previously sanded.

United States Patent 1191' Held 1 SANDING MACHINE FOR BOWLING ALLEYS [75] Inventor: Paul Held, Rochester, NY.

[73] Assignee: Allstate-Tool and Die lnc.,

Rochester, NY.

[22] Filed: June 26, 1972 [21 App]. N0.2 266,413

[111 3,815,291 June 11, 1974 Primary E.raminer-Donald G. Kelly Attorney, Agent, or Firm-l-lotfman Stone 57 ABSTRACT -A sanding machine for bowling alleys including a sanding drum mounted for rotation about an axis approximately normal to the length of the alley. The drum is journalled rigidly at the front of a unitary frame 'which rides on a bogie on the alley' and is balanced toward the rear of the bogie. The angular orientation of the frame is adjustable relative to the bogie, laterally to ensurelevel sanding, and also longitudinally to control the weight placed on the, drum. The speed of advance of the machine along the alley is controlled responsively to variations in the loadencountered by the motor that drives the drum so that the advance is slowed whenever the drumencounters a high area that requires more sanding than an area just previously sanded.

4 Claims, 7 Drawing Figures PATENTEDJUM 1 1 1914 3.8152 91 sum 1 or 4 PATENT Enm 1 1 m4 SHEET 3!!! 4 'FIG.4

FIG. 5

Pmmimuun I974 3.815291 sum nor 4 r i 1 SANDING MACHINE FOR BOWLING ALLEYS BRIEF DESCRIPTION:

This invention relates to a novel machinefor refinishing bowling alleys, and, more particularly, to a novel drum sander capable'of smooth, evenly controlled operation.

Sanding machines are widely used for refinishing bowling alleys, a task that must be done periodically to keep the alleys in proper form. Machines of the type with which the present invention is concerned include a drum extending across the width of the alley mounted at the front of a main frame for rotation on a horizontal axis. The frame rides on a bogie driven by a separate motor which governs the advance of the machine along the alley. Levelling means are-provided for tilting the drum transversely relative to the alley, thereby to ensure a level finish, and a vacuum cleaner is arranged to pick up dust and detritus from the sanding.

Most machines of this kind have been subject to certain problems, among them being a tendency for the drum to chatter occasionally and sometimes to overload its drive motor.

The invention contemplates amachine of this general type including features that make for improved and simplified operation The main frame is a unitary, rigid casting of, for example, aluminum, and the sanding drum is journalled in fixed position at the front of the frame. The frame is balanced toward the rear of the bogie, and is lifted at the rear to throw a part of its weight upon the drum. The lifting is controlled for optimum weighting of the drum, and the speed of advance of the machine along the alley is controlled to maintain an approximately constant load on the motor that drives the drum, thereby optimizing the overall performance of the machine.

To start sanding the operator first levels the frame. He then starts the three motors, one to drive the drum, one to drive the vacuum cleaner, and the third to drive the bogie. He then adjusts the lifting mechanism, raising the rear of the frame until the drum motor takes its rated current. He watches the level carefully until the bogie passes ontoa part of the alley just sanded; from there on the machine usually maintains itself level because the bogie always rides on a level-sanded surface. If desired, an automatic levelling device may be included for operating the levelling mechanism, at present it is thought that its cost would not be justifiable because the bogie rides closely behind the drum and the operator need only watch the level carefully for a very short distance, after which onlyoccasional checks are needed.

An automatic speed control is preferably provided for the bogie drive motor, and is arranged to respond to changes in the current demanded by the drum drive motor, which is of the constant speed type. When the drum encounters a high area on the alley it loads its motor more heavily than otherwise, increasing its demand for current. The speed control circuit responds to the increased demand by slowing the bogie drive motor, thereby countering the increased load on the drum and holding the current drawn by the drum motor at an approximately constant value. The speed control is, essentially, a negative feedback system looped around the working face of the drum.

DETAILED DESCRIPTION:

A presently preferred embodiment of the invention will now be described in conjunction with the accompanying drawings, wherein:

FIG. 1 is a planview, with parts broken away, sanding machine according to the: invention; v

FIG. 2 is a side elevational view of the machine shown in FIG. 1;

ofa

FIG. 3 isa longitudinal sectional view taken along the showing details of the connection between the main frame of the machine and the operators cart.

As shown, the machine includes .a unitary, rigid, main frame 10, which may be cast of aluminum, and which is generally square, like a box with an open top and an open bottom. A sanding drum 12 :is journalled in fixed position at the front of the frame 10, within it but extending below it. The drum 12 is preferably tapered slightly from its center toward both ends, say about 0.015 inch, and is slightlylonger than the width of a standard bowling alley. The taper shapes the alley, as permitted by the rules of the major bowling associations, to provide a slight centering bias to balls rolled down the alley.

To ensure smooth operation with minimum vibration and without chatter, the drum 12 is preferably dynami cally balanced, and surfaced with a fairly thick coating 13, say about one-quarter inch, of a resiliently yieldable material such as neoprene beneath the sandpaper. It is mounted at a slight angle, 2, or so, from the normal to the direction of travel of the machine. It has been found that, for reasons not presently'understood, the slight angular offset improves the sanding characteristics of the machine relative to machines in which the drum is aligned directly on the normal. The improvement is particularly evident in areas where boards of different kinds of woods are juxtaposed in the alley.

The journals 14 that support the drum 12 are preferably of the self-aligning kind, and are mounted in upwardly opening slots 16 in the side walls of the frame to allow for easy and quick removal of the drum, as required, for example, when it is desired to change from coarse to fine sand paper.

A vacuum cleaner 20 is mounted atop the frame, and itsinlet 21 is faired to draw from the alley immediately behind the drum and from the lower rear quarter of the drum itself. The drum is driven in a direction such that it sands toward the rear of the frame, clockwise as viewed in FIG. 2, and its action assists the vacuum cleaner suction; it throws the removed material into the inlet.

A drum drive motor 36, preferably fully enclosed or explosion proof, is mounted atop the frame 10 and connected to the drum 12 by a V-belt 38, or chain. The vacuum cleaner is driven by a separate motor 40, and its inlet fairing 21 extends downwardly and forwardly to the lower rear quarter of the drum 12. The dust col lection bag 44 rests on a shelf 46 .on the frame 10 immediately behind the blower 48 of the vacuum cleaner.

The bogie drive motor 50 is mounted on the bogie 28 within the frame 10, and is connected through a speed reducer 51 and a chain 52 to turn the main drive shaft 54 of the bogie. The shaft 54 is connected through sets of gears 56 and 57 to drive all four wheels 60 of the bogie synchronously. The wheels 60 are preferably provided with tires 62 of high friction material, and are fairly wide to provide adequate traction to withstand the pulling force exerted by the drum 12.

The frame is mounted on journalled supports 24 and 26 on the drive shaft 54 of the bogie. It is rotatable fore and aft on the journals, and the support 26 at the right side is vertically adjustable by a cam 34 for levelling the frame. As shown, the cam 34 is actuated manually. Automatic control is also contemplated, but is not presently thought to be economically justifiable.

The frame 10 is balanced toward the rear of the bogie so that if it is not supported it tilts to the rear, raising the drum 12 clear of the floor.

Four sets of horizontal guide wheels 64 are carried by the frame 10 at its respective corners projecting laterally to engage the inwardly facing outer walls of the gutters of the alley. The guide wheels are preferably adjustable laterally within reasonable limits, or they may be spring loaded, if desired, to allow for the usual small differences found in the overall widths of various different bowling alleys. A pair of retractable casters 66 and 67, respectively, are mounted at the front of the frame 10 to facilitate lateral shifting of the machine from one alley to another. The casters 66 and 67 are retracted while the machine is in use for sanding or polishing.

A four wheel operators cart 70 is drawn behind the main frame 10. It is attached to the frame 10 by a pair of rigid arms 72 and 73, respectively, which are firmly cantilevered at the rear of the frame and extend to pivot connections 75 and 76 on the cart. The pivot connections 75 and 76 are mounted in a vertically movable block 78 near the front of the cart immediately over its main wheels 79. A lever and bell crank arrangement 80 is provided for controllably raising and lowering the block 78, thereby selectively to raise or lower the rear of the frame 10. Raising the rear of the frame throws an increasing portion of its weight upon the drum 12, and when the block 78 is lowered to its lower limit, the drum 12 is raised clear of the floor.

The bogie drive motor 50 is adjustable as to speed, and an automatic control 82 is preferably arranged for adjusting the speed of the bogie in response to changes in the current drawn by the drum drive motor 36, slowing the bogie in response to an increase in the current and speeding itin response to a decrease. Alternatively, adjustment of the speed of the bogie drive motor 50 may be done manually by the operator in response to changes in the current drawn by the drum drive motor 36 as shown by the ammeter 84, which is conveniently mounted on an instrument panel 86.

An operators chair 87 is mounted behind the instrument panel 86 at the rear of the cart, within easy reach of the actuator levers 88 and 89 that control, respectively, the levelling cam 34 and the block 78 that raises and lowers the rear of the frame 10. The front wheels 79 of the cart are on swivels, and the rear wheels 91 are casters. When the casters 66 and 67 at the front of the frame 10 are extended down to their lower limit positions, the entire machine rests solely on the swivelled wheels 79 and the casters 66, 67, and 91; and the drum l2 and the bogie 28 are raised clear of the floor, permitting easy lateral traverse of the machine.

Dust covers and'safety shields (mostly not shown, and those shown not being separately designated) are provided in accordance with usual safety practice and for attractive dress. The drum 12 is arranged for quick and simple removal to facilitate changing its working surface in accordance with the particular type of opera tion desired at any given time. A coarse sanding surface is needed, for example, for removing varnish, and finer grit is needed for primary and finish sanding of the bare wood. Spare drums may be carried, each with its own fineness of grit, and quickly and simply interchanged. The drum drive motor 36 is movable lengthwise of the frame 10 for alternate release and re-tensioning of the Vbelt 38.

I claim:

I. A sanding machine for bowling alleys comprising:

a. a bogie and means for driving it,

b. an assembly including a frame pivoted on said bogie for tilting about an axis parallel to the axis of rotation of the bogie wheels, the center of gravity of said assembly being to the rear of the pivot connection between the frame and the bogie,

c. a sanding drum rotatably mounted on said frame in front of said bogie for rotation about an axis approximately parallel to the axis of rotation of the bogie wheels,

d. an operator's cart,

e. an attachment member rigidly attached to said frame and extending rearwardly therefrom, and

f. adjustable attachment and support meanson said operators cart for receiving said attachment member and supporting its rear portion at an adjustable height, height adjustment of said support means being effective selectively to raise and lower the rear portion of said frame selectively to transfer a portion of the weight of said assembly onto said drum.

2. A sanding machine according to claim 1, wherein said drum is angularly offset by about 2 from the axis of rotation of the bogie wheels.

3. A sanding machine according to claim 1, wherein said means for driving the bogie is controllably variable in speed.

4. A sanding machine according to claim 3, including an electric motor of the constant speed type for driving said drum, and means responsive to variations in the current drawn by said electric motor for controlling the speed of said means for driving the bogie, said controlling means being arranged to minimize variations in said current. 

1. A sanding machine for bowling alleys comprising: a. a bogie and means for driving it, b. an assembly including a frame pivoted on said bogie for tilting about an axis parallel to the axis of rotation of the bogie wheels, the center of gravity of said assembly being to the rear of the pivot connection between the frame and the bogie, c. a sanding drum rotatably mounted on said frame in front of said bogie for rotation about an axis approximately parallel to the axis of rotation of the bogie wheels, d. an operator''s cart, e. an attachment member rigidly attached to said frame and extending rearwardly therefrom, and f. adjustable attachment and support means on said operator''s cart for receiving said attachment member and supporting its rear portion at an adjustable height, height adjustment of said support means being effective selectively to raise and lower the rear portion of said frame selectively to transfer a portion of the weight of said assembly onto said drum.
 2. A sanding machine according to claim 1, wherein said drum is angularly offset by about 2* from the axis of rotation of the bogie wheels.
 3. A sanding machine according to claim 1, wherein said means for driving the bogie is controllably variable in speed.
 4. A sanding machine according to claim 3, including an electric motor of the constant speed type for driving said drum, and means responsive to variations in the current drawn by said electric motor for controlling the speed of said means for driving the bogie, said controlling means being arranged to minimize variations in said current. 